Risk-Reducing Effects of Arimidex for High-Risk Postmenopausal Women Last Years After Treatment Stops
Postmenopausal women at high risk for
breast cancer who hadn't been
diagnosed continued to get risk-reducing
benefits for at least 11 years after
they stopped taking Arimidex
preventively.
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Postmenopausal women at high
risk for breast cancer who
hadn\xe2\x80\x99t been diagnosed
continued to get risk-reducing
benefits for at least 11 years
after they stopped taking
Arimidex (chemical name:
anastrozole) preventively,
according to the latest results
from the International Breast
Cancer Intervention Study II
(IBIS-II) study.
\n
The results were presented on
Dec. 12, 2019, at the 2019 San
Antonio Breast Cancer Symposium
by Jack Cuzick, director of the
Wolfson Institute for Preventive
Medicine and head of the Center
for Cancer Prevention at the
Queen Mary University of London,
where he holds the title of John
Snow Professor of Epidemiology.
\n
Read the abstract of
\xe2\x80\x9cTen year
results of the
international breast
cancer intervention
study
II.\xe2\x80\x9d
\n
\n
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About Arimidex
Arimidex is an aromatase
inhibitor, a type of hormonal
therapy medicine used to treat
hormone-receptor-positive breast
cancer and to help reduce the
risk of the cancer coming back
(recurrence) in postmenopausal
women.
\n
Aromatase inhibitors work by
stopping the body from producing
estrogen, which limits the
amount of estrogen available to
stimulate
hormone-receptor-positive breast
cancer cells to grow.
\n
Other hormonal therapy
medicines, including Aromasin
(chemical name: exemestane),
tamoxifen, and Evista (chemical
name: raloxifene), have been
shown to reduce the risk of
developing
hormone-receptor-positive breast
cancer in high-risk women who
haven\xe2\x80\x99t been
diagnosed. So, researchers
wanted to know if Arimidex could
be used in the same way.
\n
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About the IBIS-II study
The IBIS-II study included 3,864
women considered to be at high
risk of developing breast
cancer. The women were
considered to be at high risk
because they had:
\n
-
\n
- a strong family history of breast cancer \n
- been diagnosed with benign (non-cancerous) breast disease, such as lobular carcinoma in situ \n
- dense breasts \n
None of the women in the study
took hormone replacement
therapy.
\n
Half the women were randomly
assigned to take Arimidex for 5
years, and the other half were
assigned to take a placebo (a
dummy pill that looked just like
Arimidex).
\n
Overall, 74.6% of the women
taking Arimidex and 77% of the
women taking the placebo took
the medicine for the full 5
years.
\n
In 2013, the researchers
reported results with about 7
years of follow-up, showing that
women who took Arimidex were 53%
less likely to develop breast
cancer than women who
didn\xe2\x80\x99t take Arimidex.
\n
The results reported at the 2019
San Antonio Breast Cancer
Symposium have a median
follow-up of 10.9 years, which
means half the women were
followed for less than 10.9
years and half the women were
followed for longer periods of
time.
\n
The new results show that women
who took Arimidex were 50% less
likely to be diagnosed with
breast cancer than women who
didn\xe2\x80\x99t take Arimidex.
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\xe2\x80\x9cThe 50% reduction in
likelihood of breast cancer
incidence after 10.9 years of
follow-up is slightly less than
the 53% reduction we reported
after the first 7 years of
follow-up, but it is still a
significant effect and larger
than that seen for
tamoxifen,\xe2\x80\x9d said
Cuzick. \xe2\x80\x9cAnother way
to consider the result is that
it translates into an estimated
29 women needing to be treated
with anastrozole for 5 years to
prevent one breast cancer during
treatment and in the next 5
years.
\n
\xe2\x80\x9cThis is far fewer
women than the estimated 49
women that need to be treated
with tamoxifen for 5 years to
prevent one breast cancer in the
same time period,\xe2\x80\x9d
Cuzick continued.
\xe2\x80\x9cTherefore, our new
results strongly suggest that
anastrozole should be the
preferred therapy for breast
cancer prevention in
postmenopausal women at
increased risk for the disease,
with tamoxifen used for women
who experience severe side
effects from anastrozole. It is
exciting to see that anastrozole
has a continued impact on breast
cancer incidence even after
stopping treatment, as this
strengthens the case for its use
as a breast cancer prevention
therapy.\xe2\x80\x9d
\n
Cuzick emphasized that the
protective benefits of Arimidex
are only for
hormone-receptor-positive breast
cancer and DCIS, not for
hormone-receptor-negative
disease.
\n
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Side effects
In the IBIS-II study, about 75%
of the women in each treatment
group took the medicine for the
full 5 years. This rate is
similar to other studies that
have found about 25% of women
don\xe2\x80\x99t complete the
full 5-year course of hormonal
therapy, mainly because of side
effects.
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Common side effects of Arimidex
include:
\n
-
\n
- bone and joint pain \n
- nausea \n
- vomiting \n
- hot flashes \n
- weakness \n
- fatigue \n
Because Arimidex lowers the
amount of estrogen in the body,
less estrogen reaches bone
cells, which can lead to bone
thinning and weakening and a
higher-than-average risk of
broken bones.
\n
In the IBIS-II study,
researchers measured the
women\xe2\x80\x99s bone density
before the study started and any
woman who had low bone density
was prescribed a bisphosphonate,
a type of medicine used to
prevent or treat osteoporosis.
Zometa (chemical name:
zoledronic acid) and Boniva
(chemical name: ibandronate) are
two common bisphosphonates.
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For the 2019 results, Cuzick
reported that there were no new
side effects beyond those
reported in 2013, which were
muscle aches and pains and hot
flashes.
\n
\xe2\x80\x9cNo excess of
fractures or other serious side
effects were seen with
anastrozole,\xe2\x80\x9d he
said.
\n
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What this means for you
If you have a
higher-than-average risk of
breast cancer, it makes sense to
do everything you can to keep
your risk as low as it can be.
There are lifestyle choices you
can make, including:
\n
-
\n
- maintaining a healthy weight \n
- exercising regularly at the highest intensity possible \n
- limiting or avoiding alcohol \n
- limiting processed foods and foods high in sugar \n
- eating healthy, nutrient-dense food \n
- not smoking \n
You and your doctor also may be
considering medicine to reduce
your risk. Talk to your doctor
about your preferences as well
as the risks and benefits of
each medicine. Together, you can
make the best choice for your
unique situation.
\n
For more information on
medicines used to reduce the
risk of
hormone-receptor-positive breast
cancer, visit the
Breastcancer.org
Hormonal Therapy
pages.
\n
To talk with others who are at
higher-than-average risk for
breast cancer, join the
Breastcancer.org Discussion
Board forum
High Risk for Breast
Cancer.
\n
Written by:
Jamie DePolo, senior editor
\n
Reviewed by:
Brian
Wojciechowski,
M.D., medical adviser
\xe2\x80\x94 Last updated on February 22, 2022, 10:06 PM
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